growing lettuce

Growing Lettuce: Plant and Harvest Guide

Growing lettuce is not difficult. There are two major types of lettuce: head and loose-leaf. Both grow well in similar conditions when the temperatures are cool but not freezing. Harvest times vary by variety, but all lettuce has a fairly short growth period, so you can enjoy your homegrown lettuce within a couple of months of planting.

Lettuce is a hardy annual that prefers to grow in cooler weather, with substantial sunshine and frequent watering. Plant lettuce in early spring, because it grows best in temperatures of  73° F or below. Harvesting lettuce is as easy as removing the leaves before it reaches full maturity.

If you would like to grow your own lettuce, the process is fairly simple. You can get started planting lettuce with just a little know-how. Keep reading to learn more.

Related: Easiest Vegetables to Grow

Growing Lettuce

The Best Growing Conditions for Lettuce

Whether starting seeds indoors or outdoors, the growing conditions for lettuce need to be just right. While lettuce is hardy, it can also be finicky. It’s important to begin your lettuce plants at the proper time, as well as in the right amount of sunlight, the right kind of soil, and with fertilizer and proper watering.

1. Starting your Seeds Indoors

Because lettuce is a cold weather-loving plant, you are not required to begin your lettuce seeds indoors in the spring. Lettuce grows well when planted from seed directly into outdoor soil that is just warm enough to be workable. Starting your lettuce seeds indoors is a step you may skip, though some gardeners prefer to begin their harvest as early as possible, especially when beginning when the outdoor conditions are too hot, and you want to get a jumpstart for your late autumn or winter harvest. Starting your seeds indoors may also be a good idea if you want to plant lettuce successively.

There is some debate around the best soil for starting lettuce seed indoors, but expert gardeners have had success beginning lettuce seeds indoors in both peat pots and potting soil. Make sure your lettuce seedlings get plenty of light, either direct sunlight in a greenhouse, a window with all-day sun, or under artificial lights. Lettuce also needs to be watered frequently.

Because lettuce seeds are so small and difficult to control, beginning lettuce seeds indoors will allow you to reduce crowding by separating seedlings that sprout too close together. This process may be much easier to handle in indoor pots than on hands and knees in a garden bed.

Once your lettuce plants reach 2-3 inches in height, it is time to transplant outdoors.

2. When to Plant Lettuce Outdoors

The ideal time for planting lettuce outside varies by region. It is always best to check with your local USDA Extension office for the best planting times in your area before planting. USDA Extension offices are located in courthouses, post offices, or other local government buildings and provide research-based knowledge to assist in agriculture enterprises. In the list below, planting times for lettuces are arranged by USDA hardiness zones for 2021.

  • Zones 3-4: April 15 – June 1 or Aug. 1 – 15
  • Zones 5-6: Apr 1 – May 15 or August 1 – 15
  • Zone 7: Feb.15 – March 10 or Aug 1 – 15
  • Zones 8-9: vary more than other zones by specific region. It’s best to begin in late February for spring harvest or plant in late September for a winter crop. 

Loose-leaf lettuces and head lettuces grow around the same schedules in cooler climates, but they vary in hotter climates. Lettuce grows best when the temperatures average 73° F during the day and 45° F at night. You can begin the growing season early using a floating row cover, which offers a few degrees of frost protection and provides a warmer growing environment. At temperatures near freezing, young plants won’t become damaged, but growth will be slow. Optimum temperatures for seed germination range from 68° to 77° F. At higher temperatures, lettuce may bolt and become bitter. Loose, fluffy heads and tip burn may also be caused by high temperatures. 

Transplant your lettuce once your plant has about 4-6 mature leaves. When transplanting lettuce plants from indoors to outdoors, it is best practice to harden your plants first. Expose them to outdoor conditions a little at a time for 7-10 days before planting. 

Finally, planting lettuce as close together as possible helps to combat weed growth before it starts. It also helps to keep the soil below moist for as long as possible.

growing lettuce

The Best Soil for Growing Lettuce

Always begin with soil testing. This is easily accomplished either by contacting your local extension office, or you can purchase a simple test online, at a nursery, or a home and garden center.

Ideally, your garden bed should consist of rich, sandy loam or muck soil with a pH level of 6-7, and it should be exposed to plenty of sunshine.

Heavy clay or sandy soils can be improved by adding organic material such as compost, manure, or leaf mold. Lettuce grows best in soil that is rich in nitrogen. Compost heavy in green material can easily amend soil that is lacking in nitrogen. 

However, the preparation of your soil is just as important as adding fertilizer and soil amendments. Before working the soil, make sure it is moist but not thoroughly wet. The soil in your garden bed should absorb water readily, not form a crust upon drying, and drain sufficiently so that it does not become waterlogged.  Porous soil contains more air, which is necessary for vigorous root growth. If your soil is tough or compacted, use a shovel, rototiller, metal bow rake, or all of them together to loosen the top 1 to 2 inches of soil. Rake the area to remove weeds and old crop debris. Be sure to dig out weed roots as they can easily regrow.

Keep weeds managed when plants are established by plucking them gently at the base. This will remove most of the root system, slowing down or preventing regrowth and spread.  But be careful not to disturb the gentle roots of your lettuce. 

Finally, keep the soil around your lettuce cool and moist. Frequent watering is a must for lettuce, and soil can be cooled if it gets too warm by adding a layer of natural mulch or straw.

Related: Easiest Vegetables to Grow

watering lettuce

How to Plant Lettuce

Lettuce seeds should be planted ⅛ to ¼ inch deep. Lettuce plants have shallow roots that love plenty of sunshine. Planting any deeper will cause you to lose your seeds. Make sure the soil has no stones or other obstructions in it before planting.

Be sure to plant lettuce in a location that gets 6 or more hours of sunshine per day. The more sunshine your lettuce is exposed to, the better it will grow.

Spacing or thinning your lettuce is dependent upon variety:

  • Loose-leaf lettuce: 4 inches apart
  • Romaine and butterhead lettuce: 8 inches apart
  • Crisphead lettuce: 16 inches apart

Finally, be sure to water through when planting seeds or trans

planting immature lettuce plants.

How to Feed and Water Lettuce

Properly Fertilizing Lettuce

If you have already added compost or fertilizer to your soil before planting, that is a good start for your lettuce. But lettuce is a hungry plant as well as a thirsty one, so be sure to add a balanced, natural fertilizer every 2 weeks. A well-balanced fertilizer should contain equal parts nitrogen, phosphorus, and potassium. If you choose to use a granular fertilizer, be sure to water it down to half strength.

While many publications advise gardeners to feed their lettuce plants extra nitrogen, it may not be the best advice. 

One of the best studies about fertilizer on lettuce was conducted at the University of Florida, along with the Florida Agricultural Statistics Service. The study showed the relationship between different nutrients that were introduced to crisphead lettuce growing in organic soil over the past 40 years. Crisphead lettuce is a cash crop in Florida, growing beautifully in organic muck soil in the winter. The study shows that while crisphead lettuce was historically believed to require more nitrogen, the crops produced better with balanced fertilizers. The crisphead also grew more hearty with liquid fertilizers that penetrated the soil 2-3 inches than with granulated fertilizers. 

Watering Lettuce

Lettuce consists mostly of water which makes it a thirsty plant. All varieties of lettuce have shallow roots, particularly loose-leaf lettuce.

All lettuce needs to be watered frequently as opposed to deeply. While commercial growers often use an above-ground irrigation system, it’s not necessary to spend the money on one of these at home. Watering lettuce twice a week is sufficient in most areas, but in higher temperatures, you may want to water 3-4 times a week to keep your lettuce from scorching.

growing lettuce

How Long it Takes for Lettuce to Grow

Lettuce generally takes anywhere from 30 days to 8 weeks to reach full maturity.

First, lettuce seedlings only take about 7-10 days to emerge. If you are beginning your lettuce inside, it only takes about 3-6 weeks depending on the variety to start your lettuce plants indoors. At this point, they will be mature enough to plant in your garden bed.

While most lettuce takes about 45-55 days to mature, leaf lettuce is the fastest and easiest to grow, and it often matures in less than 30 days. Alternatively, Romaine matures around 75 to 85 days, and crisphead matures around 70 to 100 days. This is why some gardeners choose to grow a variety of lettuces, and it is also why many choose to plant lettuces successively. 

Preventing Bugs, Animals, and Diseases from Destroying your Lettuce 

Several animals or diseases could damage your lettuce crops. Despite that, it is best not to spray your plants with any poisons as they are more likely to cause harm to children or pets than to garden pests.

  • Animals: Rabbits, voles, woodchucks, deer, chipmunks, squirrels

To keep animals away, a fence or mesh barrier helps. Also, keeping the garden as close to your home is a great idea. Pests are less likely to come around if there are humans and pets nearby. While some people swear by using soap or artificial predator urine to keep pests away, there have been few studies to show success with either of these methods. 

  • Insects: Cutworms, flea beetles, aphids, leafhoppers, slugs

Using an organic insecticide is one of the best options. It will not only keep damaging chemicals off your homegrown vegetables, but it will also keep from harming children and pets. It may be a good idea to grow barrier plants such as chives or garlic between your lettuce plants to prevent pests such as aphids. 

  • Diseases: Bottom rot disease and aster yellows spread by the leafhopper insect

Bottom rot is difficult to treat, but it can be prevented by rotating your crops seasonally. Since lettuce is an annual, try growing it in a different spot year to year, with three years in between replanting in the same spot. Keeping plants thinned and keeping the garden beds free of rotting materials is another method of reducing the chances of bottom rot.

Leafhopper insects will not come around if you are already using an organic insecticide. They can also be dissuaded from infesting your garden bed if you use row covers.

curly lettuce

When and How to Harvest your Lettuce

Harvest head lettuce once the heads reach an acceptable size, color, and firmness. Leaving them in the garden too long may result in bolting, sunburn, or possible damage from freezing. They may also have a woody or bitter taste if not removed at the proper time. You’ll know your head lettuce is mature enough to harvest once it forms the pale round head familiar from the supermarket. Ideally, you’ll pick the lettuce when the outer leaves are pale green before they turn brown. If they do change to brown, or a flowering stalk appears, harvest immediately. You can remove them from the ground by cutting the head off with a sharp, clean knife directly at the stem. 

Leaf lettuce can be harvested either all at once or over a long period of time by breaking off the outside leaves and allowing the interior leaves to continue to develop. Since it has a fairly short shelf life, it should be refrigerated as soon after harvest as possible. Harvest by cutting the outer leaves one by one when they’re large enough to use and allow the inner leaves to develop. Another method for baby lettuce is to cut all of the leaves a few inches above the soil, making sure not to cut the growing point.

Romaine lettuce will begin to look as it does in the supermarket as the maturity date nears. But experts recommend giving the heads a good squeeze to check. An immature romaine head is loose and compresses easily, while an overly ripe head feels hard to the touch. Harvest Romaine when it reaches between 6 and 8 inches tall, with leaves that begin to tighten. Harvesting first thing in the morning is ideal because the lettuce is crisper in the morning than it is later in the day. Cut the romaine heads off just above the soil line and below the lower leaves, using a sharp, clean knife. Cutting the romaine allows the plant to possibly grow additional lettuce. As with head lettuce, make sure to use a clean, disinfected knife when harvesting.

How Many Times you Can Harvest Lettuce from One Plant

After the initial harvest, most varieties of lettuce will be able to regrow within a few weeks as long as the crop is kept healthy with adequate fertilizer, watering, temperature control, and sunlight. 

Leaf lettuces, particularly the large leaf varieties can be harvested over and over until they begin to flower and seed. You can accomplish this by removing only the outer leaves, leaving the inner leaves to continue growing. At this time, a larger stock will appear in the center, and you will no longer be able to harvest.

Head lettuces and romaine lettuces generally only produce one crop per season. That’s why it is recommended by expert gardeners to plant these crops successively.

Red lettuces tend to last longer than green and can often be harvested 3-4 times in a season. After the initial harvest, each additional harvest tends to produce less, so don’t worry that there is something wrong with your plant. Most likely, there is not. 

After the final harvest of the season, don’t forget to dig out your lettuce plants. Remove the bolted lettuce plants right after harvesting the last remaining leaves. Grip the base of the stem to pull them up. Then you can toss them into your compost heap.

harvest lettuce

Fun Facts

Despite its cold-weather nature, 30% of the lettuce we enjoy in the US is grown in Florida, because it grows beautifully throughout the winter in zones 8-10.

There were once 1,100 named lettuce varieties on the market, before the late 19th century. Then, scientists began to document each variety, concluding that there were no more than 140 distinct varieties. 

Lettuce belongs to the daisy family, along with sunflowers, mint, mums, and dandelions.